The present invention relates to an information transfer system. More particularly, the invention relates to a system for sequentially transferring information from a control unit to a controlled unit having a plurality of circuit stages.
When it is required to operate a controlled unit such as, for example, an input-output control system according to an information, by transferring the information to the controlled unit for a control unit of the program control type such as, for example, a central processing unit, the controlled unit is provided with circuits such as registers for storing or setting the transferred information. The information is transferred from the control unit via a data bus and is stored or set in a circuit designated by the control unit according to the information. Therefore, if there are many circuits for storing or setting the transferred information, the information routes increase in accordance with the number of circuits, resulting in a complex and complicated circuit configuration.
If each circuit of the controlled device is formed to sequentially shift the transferred information to the next-successive circuit, in the manner of a shift register, the information transferred from the control unit may easily be set in the circuits. However, in order to transfer a new information to the relevant circuit, just like altering the storing or setting information of a selected one of the circuits, a direct information route from the data bus is required. In such a case, although information may easily be transferred only by shifting it, the succeeding information transfer is exactly the same as before.
The principal object of the invention is to provide an information transfer system for transferring new information to a selected circuit via a data bus without altering the information content of other circuits.
An object of the invention is to provide an information transfer system of a structure more simple than those of known similar systems and which overcomes the shortcomings of such known systems.
Another object of the invention is to provide an information transfer system of simple structure, which permits the alteration of information in a selected circuit without altering information stored in other circuits connected in circuit therewith and without the need for a specific information line for transferring the information to the selected circuit.
Still another object of the invention is to provide an information transfer system utilizing a data bus for controlling a plurality of circuit stages and utilizing such bus for transferring altered information to a selected one of the circuit stages thereby simplifying the circuit arrangement of the information transfer system.
Yet another object of the invention is to provide an information transfer system of simple structure which functions efficiently, effectively and reliably to transfer information and altered information to a plurality of circuits and to a specified circuit, respectively.